As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CMH - CREW REPORTED SMOKE IN CABIN. RETURNED CMH WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND AUXILIARY POWER UNIT LEAKING OIL AND EVIDENCE OF OIL INGESTION INTO APU INLET. ACCOMPLISHED MCM CARD 21-96-01 AND MCM CARD 21-92-12. SYSTEM GROUND CHECK NORMAL OPERATION.